Threading device of sewing machine

ABSTRACT

A threading device of a sewing machine includes a thread inserting base formed with a thread path hole having a thread inserting port opened toward an outer side of a sewing machine frame, and further formed with an air path hole which joins the thread path hole in the vicinity of the thread inserting port, an air supply device coupled to the air path hole to supply compressed air, and illuminating means provided on the sewing machine frame to irradiate a joining portion of the thread path hole and the air path hole. The thread inserting base includes a transparent member through which at least the joining portion of the thread path hole and the air path hole can be visually recognized.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent ApplicationNo. 2006-291333 filed on Oct. 26, 2006, the entire content of which isincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a threading device of a sewing machinewhich feeds a looper thread toward a looper by utilizing air.

BACKGROUND ART

A threading device of a sewing machine inserts a thread into a threadhole of a looper which forms a seam by cooperating with a needle. In thethreading device, there is known a technique in which an opening portionis provided on an outer side of a sewing machine frame, and compressedair is sprayed toward an inner part of a threading tube which is a pathfor a thread to pass through an inner side of the sewing machine frame,whereby the thread is fed toward the looper (see, e.g., Japanese PatentNo. 2865470).

In this threading device, the air is compressed by an air pumpinterlockingly with a manual operation of a lever (see FIG. 5), and isdischarged from a tip of a nozzle attached obliquely to a side surfaceof the threading tube, whereby the air is supplied toward the inner partof the threading tube.

The nozzle is obliquely attached at a position slightly on a downstreamside from the opening portion of the threading tube so that the air isdischarged from the tip at a position slightly on an inner side of thethreading tube, i.e., the downstream side from the opening portion fromwhich the thread is inserted. When inserting a tip end of the threadsupplied from a thread supply source from the opening portion throughthe threading tube, the tip end of the thread is inserted until itreaches the downstream side of the tip of the nozzle, and the air isdischarged by operating the lever, the thread is efficiently fed towardthe downstream side of the thread path.

In the field of the sewing machine, moreover, there is known a techniqueto provide a transparent member on a thread path (see, e.g., JP 8-280965A).

In the sewing machine disclosed in Japanese Patent No. 2865470, a threadinserting base which supports the threading tube is formed of an opaquemember. Therefore, it is difficult for a user to visually check anamount of the thread inserted into a thread inserting port from theouter side of the sewing machine frame. Accordingly, in the event thatthe amount of the thread inserted into the thread inserting port isinsufficient, there is a problem that the compressed air cannot besprayed directly toward the thread so that the thread cannot be fedsmoothly even if the lever for the air pump is operated repetitively.Consequently, there is a problem that the lever is uselessly operatedmany times, resulting in a decrease in working efficiency.

Even if the technique disclosed in the JP 8-280965 A is utilized toprovide a transparent member for the thread path portion so that thethread inserting port is formed of the transparent member, there is aproblem that, because threads to be used in the sewing machine are thinand have light colors such as white in many cases, it is difficult tosee an inner side of the transparent member, resulting in adeterioration in workability.

SUMMARY

It is an object of the invention to efficiently and easily carry out athreading work for inserting a thread through a looper with a simplestructure.

According to a first aspect of the invention, a threading device of asewing machine includes a thread inserting base formed with a threadpath hole having a thread inserting port opened toward an outer side ofa sewing machine frame, and further formed with an air path hole whichjoins the thread path hole in the vicinity of the thread inserting port,an air supply device coupled to the air path hole to supply compressedair, and illuminating means provided on the sewing machine frame toirradiate a joining portion of the thread path hole and the air pathhole. The thread inserting base includes a transparent member throughwhich at least the joining portion of the thread path hole and the airpath hole can be visually recognized.

According to a second aspect of the invention, a portion of the threadinserting base around the thread inserting port may be formed of atransparent glass material.

According to a third aspect of the invention, the illuminating means mayinclude an LED disposed on an inner side of the sewing machine frame.

According to a fourth aspect of the invention, the air supply device mayinclude an air nozzle coupled to the air path hole, an air generatingmember coupled to the air nozzle to supply the air by expanding andcontracting, and an operating member which expands or contracts the airgenerating member by being operated.

According to a fifth aspect of the invention, the operating member maybe operably disposed on a front side of the sewing machine frame.

According to the first aspect of the invention, the thread insertingbase includes the transparent member through which at least the joiningportion of the thread path and the air path can be visually recognizedfrom the outside of the sewing machine frame. Therefore, it is possibleto easily and visually recognize whether the thread inserted from thethread inserting port is reached to a depth that is sufficient for thethread to be efficiently fed by the air discharged from the air path.Consequently, it is possible to prevent a time-wasting air supplyingoperation of the air supply device like in the background art in whichthe operator cannot visually recognize whether the thread is inserted toa sufficient depth from the thread inserting port or not. Thus, thethreading work can be carried out easily and efficiently. Moreover, theilluminating means irradiates the joining portion of the thread path andthe air path. Thus, it is possible to enhance visibility of the threadinserted from the thread inserting port.

In addition, in a case in where a plurality of thread inserting ports isprovided, the thread inserting port into which the thread should beinserted can be shown to an operator by turning on the associatedilluminating means. In such a case, the threading work can be carriedout more easily.

The thread inserting port is required to have such a strength as toprevent an abrasion or cutting from being caused by a friction of thethread supplied through the thread inserting port. However, according tothe second aspect of the invention, because the thread inserting port isformed of a glass material, it is possible to ensure hardness that issufficient to provide the required strength while enhancing visibilityfrom an outer side. Consequently, it is possible to prevent threadbreaking or thread supplying failures from being caused by a worn awayportion of the thread inserting port at which a lower thread may becaught. Thus, it is possible to ensure a smooth thread path.

According to the third aspect of the invention, the operator canvisually recognize the thread reliably. Thus, the threading work can becarried out easily and reliably.

According to the fourth and fifth aspects of the invention, thethreading work can be carried out with a simple structure and a cost canbe reduced. Furthermore, it is possible to effectively utilize the innerpart of the sewing machine frame which is narrowed by various devices.Thus, it is not necessary to increase a size of the sewing machineframe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a sewing machine according toan exemplary embodiment of the invention.

FIG. 2 is a perspective view showing a threading device according to theexemplary embodiment.

FIG. 3 is a sectional view showing the threading device according to theexemplary embodiment.

FIG. 4 is a schematic view showing another exemplary embodiment of theinvention.

FIG. 5 is a schematic explanatory view showing a threading operation inthe background art.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the invention will be explainedwith reference to FIGS. 1 to 4. The following exemplary embodiments andthe drawings do not limit the scope of the invention. In the exemplaryembodiments, directions of respective portions of a sewing machine M aredefined by X, Y and Z axes shown in the drawings. In a state in whichthe sewing machine M is disposed on a horizontal plane, a Z-axisdirection is a vertical direction (an up-and-down direction), a Y-axisdirection is a longitudinal direction of an arm portion 2 a (aright-and-left direction), and an X-axis is a front-and-rear directionwhich is horizontal and is orthogonal to the Y-axis direction.

(Overall Structure)

FIG. 1 is a schematic perspective view of the sewing machine M having athreading device 1 according to an exemplary embodiment.

As shown in FIGS. 1 and 2, the threading device 1 includes a threadinserting base 12 formed with opening portions 10 opened toward an outerside of a sewing machine frame 2, and an air supply device 5 whichsupplies compressed air to an air path hole 14 of the thread insertingbase 12.

(Sewing Machine Frame)

As shown in FIG. 1, the sewing machine frame 2 includes the arm portion2 a which supports a needle 3 so as to be movable in the verticaldirection and forms an upper part the sewing machine frame 2, a bedportion 2 b which is mounted on a sewing machine table (not shown) andforms a lower part of the sewing machine frame 2, and a vertical drumportion 2 c which couples the arm portion 2 a and the bed portion 2 band is set upright in the vertical direction (the Z-axis direction)orthogonal to the longitudinal direction of the arm portion 2 a and thebed portion 2 b. An external shape of the sewing machine frame 2 is aC-shape when seen from a front.

A looper LP is disposed inside the bed portion 2 b below the needle 3,and forms a seam by cooperating with the needle 3. The looper LPincludes an extended portion LP1 which is inserted through a loop of anupper thread formed below a cloth (a workpiece) when the needle 3penetrating through the cloth is lifted upward. A thread hole (notshown) is formed at a tip portion of the extended portion LP1. A lowerthread (a looper thread) T to be entangled with the upper thread to forma seam is inserted through the thread hole of the extended portion LP1.The lower thread T is fed through a predetermined thread path inside thesewing machine frame 2 from the threading device 1, and is insertedthrough the thread hole.

(Air Supply Device)

The air supply device 5 includes an air pump (an air generating portion)6 which compresses air with an extensible and hollow bellows portion, anair nozzle 8 having a tip portion 8 a from which the air supplied fromthe air pump 6 is discharged, an air supply tube 7 through which the aircompressed at the air pump 6 is fed toward the air nozzle 8, and a lever9 (an operating portion) which is connected to one end of the bellowsportion and actuates the air pump 6 when it is manually operated by anoperator.

The air pump 6 is disposed inside the vertical drum portion 2 c of thesewing machine frame 2. The air pump 6 compresses the air when thebellows portion contracts in accordance with the manual operation of thelever 9.

The air nozzle 8 obliquely penetrates a side wall of the threadinserting base 12 toward a downstream side of a thread path hole 13 insuch a manner that the lower thread T inserted from the opening portion10 can be fed toward a side of the looper LP. The tip portion 8 a of theair nozzle 8 is placed on the same surface as an internal wall of thethread path hole 13 inside the thread inserting base 12 or is at aposition slightly retracted therefrom so as not to be protruded into thethread path hole 13 from the internal wall surface.

The lever 9 shown in FIG. 1 includes a tip portion which protrudes froma front surface of the sewing machine frame 2 and movable in thevertical direction, an intermediate portion rotatably supported on thesewing machine frame 2, and a rear end portion which extends toward aninner side of a cover and is coupled to a lower end of the air pump 6.When carrying out a threading operation, the lever 9 is operated withthe cover being opened. The lever 9 is pushed downward in a direction ofan arrow shown in FIG. 2, and is then returned automatically to anoriginal upper position.

(Thread Inserting Base)

Next, the thread inserting base 12 according to the exemplary embodimentwill be described in detail.

As shown in FIGS. 2 and 3, the thread inserting base 12 is formed withthe thread path hole 13 having the opening portion 10 which is openedtoward the outer side of the sewing machine frame 2 and serves as a portfor inserting the thread T, and further formed with the air path hole 14which joins the thread path hole 13 in the vicinity of the openingportion 10.

The thread path hole 13 penetrates the thread inserting base 12substantially in the Z-axis direction, and a lower end thereof iscoupled to a thread guide tube 16 which leads the thread T to the looperLP. The air path hole 14 is provided toward an inner part of the threadpath hole 13 from the inner side of the sewing machine frame 2.

The opening portion 10 is provided with a thread inserting port member11 which prevents a peripheral edge of the opening portion 10 from beingworn away by the lower thread T supplied to the looper LP through theopening portion 10. As shown in FIGS. 2 and 3, an opening of the threadinserting port member 11 is enlarged toward the outer side of the sewingmachine frame 2 like a funnel. In order to prevent the wear, the threadinserting port member 11 may be formed of a metal or a ceramic.

The thread inserting base 12 includes a transparent member through whichat least the joining portion of the thread path hole 13 and the air pathhole 14 can be visually recognized from the outer side of the sewingmachine frame 2. According to the exemplary embodiment shown in FIGS. 1to 3, the entire body of the thread inserting base 12 is formed of atransparent synthetic resin such as acryl.

The thread inserting base 12 is provided with a indicating portion 15which indicates an amount the lower thread T to be inserted from theopening portion 10. This indicating portion 15 serves as a referencemark for the operator to visually and easily recognize, from the outerside of the sewing machine frame 2, whether the tip end of the lowerthread T is inserted and reached a depth that is sufficient for thelower thread T to be efficiently fed by the air discharged from the tipportion 8 a of the air nozzle 8. In the exemplary embodiment, theindicating portion 15 is provided at a height on a lower side of thejoining portion of the thread path hole 13 and the air path hole 14,i.e., on a downstream side of the joining portion in the path forsupplying the lower thread T.

As shown in FIGS. 3 and 4, moreover, an LED (Light Emitting Diode) 20 isfixedly disposed in the sewing machine frame 2 as illuminating means forirradiating light toward the joining portion of the thread path hole 13and the air path hole 14. An optical axis V of the LED 20 extends fromthe inner side (a rear side) of the sewing machine frame 2 toward theouter side of the sewing machine frame 2, i.e., the operator side. Atransmitting hole K or a transparent member (not shown) which fills thetransmitting hole K is provided at a portion of the sewing machine frame2 where it faces against the irradiated light from LED 20. Accordingly,the LED 20 irradiates the light on the transparent thread inserting base12 from the rear side, whereby a shadow of the thread in the threadinserting base 12 becomes clear so that the operator can easily see thethread through the thread inserting base 12.

(Explanation of Operation)

Next, description will be given to an operation of the threading device1 of the sewing machine having the above configuration.

First of all, when inserting the lower thread T for the looper LP fromthe opening portion 10, the operator inserts the tip end of the lowerthread T reeled out from a lower thread supply source (not shown)provided on the outer side of the sewing machine frame 2 into theopening portion 10. At this time, because the thread inserting base 12is formed as the transparent member (e.g., acryl) and the joiningportion is illuminated by the LED 20, the operator can carry out athreading work while visually checking the tip end of the lower thread Tinserted from the opening portion 10 form the outer side of the sewingmachine frame 2 (see an arrow A in FIG. 3).

After visually recognizing that the tip end of the lower thread T isinserted to the indicating portion 15, the tip portion of the lever 9 isvertically moved so that the air pump 6 coupled to the rear end of thelever 9 actuated to expand and to contract. Consequently, the compressedair is discharged from the tip portion 8 a of the air nozzle 8, and thelower thread T is fed toward the downstream side of the thread supplypath, i.e., toward a side of the looper LP.

As described above, according to the threading device 1 of the sewingmachine of the exemplary embodiment, regions on the upstream side andthe downstream sides of a portion where the tip portion 8 a of the airnozzle 8 is placed in the thread supply path are formed of a transparentmember. Therefore, it is possible to easily and visually recognize, fromthe outer side of the sewing machine frame 2, whether the lower thread Tinserted through the opening portion 10 is inserted and reached a depththat is sufficient to be efficiently fed by the compressed airdischarged from the tip of the air nozzle 8 or not. Thus, time-wastingoperations of the air pump 6 can be prevented so that the threading workcan be carried out easily and efficiently. Moreover, the indicatingportion 15 which indicates the amount the thread to be from the openingportion 10 is provided. Therefore, it is possible to easily decidewhether the lower thread T is inserted to a sufficient depth that thelower thread T can be efficiently fed by the air discharged from the tipof the air nozzle 8.

In addition, it is possible to illuminate the joining portion by turningON the LED 20, and the operator can easily and visually recognize thethread inside the joining portion formed of a transparent member.Specifically, because the light is irradiated toward the operator side(the outer side) from the rear side (the inner side of the sewingmachine), it is possible to obtain such an illuminating effect that thethread inserted from the opening portion 10 can be seen more easily.Consequently, the threading work can be carried out easily and reliably.

The thread inserting port member 11 may be formed of a transparent glassmaterial. In this case, the amount of the lower thread T inserted fromthe opening portion 10 can be visually recognized more clearly from theouter side of the sewing machine frame 2. Moreover, both the threadinserting port member 11 and the thread inserting base 12 may be formedof a glass material so as to be in a one-piece structure.

The illuminating means may be other than LED. e.g., an ordinary lamp,and may irradiate light toward the joining portion from the outer sideof the sewing machine frame.

In a case where a plurality of thread inserting ports are provided forsupplying the thread to an upper looper and a lower looper, etc., it ispossible to provide a guide function which indicates an order ofinserting the thread by sequentially turning on lights based on acontrol signal sent from a control portion (not shown). In this case, itis possible to enhance an operability of the threading work.

In addition, the indicating portion 15 may be provided on an outersurface of the thread inserting base 12 or on an inner part thereof.

While description has been made in connection with exemplary embodimentsof the present invention, it will be obvious to those skilled in the artthat various changes and modification may be made therein withoutdeparting from the present invention. It is aimed, therefore, to coverin the appended claims all such changes and modifications falling withinthe true spirit and scope of the present invention.

1. A threading device of a sewing machine comprising: a thread insertingbase formed with a thread path hole having a thread inserting portopened toward an outer side of a sewing machine frame, and furtherformed with an air path hole which joins the thread path hole in thevicinity of the thread inserting port, wherein the thread inserting baseincludes a transparent member through which at least a joining portionof the thread path hole and the air path hole can be visuallyrecognized; an air supply device coupled to the air path hole to supplycompressed air; and illuminating means provided on the sewing machineframe to irradiate the joining portion of the thread path hole and theair path hole,
 2. The threading device according to claim 1, wherein aportion of the thread inserting base around the thread inserting port isformed of a transparent glass material.
 3. The threading deviceaccording to claim 1, wherein the illuminating means includes an LEDdisposed on an inner side of the sewing machine frame.
 4. The threadingdevice according to claim 1, wherein the air supply device comprises: anair nozzle coupled to the air path hole; an air generating membercoupled to the air nozzle to supply the air by expanding andcontracting; and an operating member which expands or contracts the airgenerating member by being operated.
 5. The threading device accordingto claim 4, wherein the operating member is operably disposed on a frontside of the sewing machine frame.